Montezuma II, 22 year old, ascended the throne of Tenochtitlán. The first Spanish expedition to the coast of Mexico took place in 1517. They reached the Yucatan peninsula after leaving Cuba and discovered a large town of a size unknown in Cuba or Hispaniola. The native population of Central Mexico at that time has been estimated at 25 millions. Another expedition led by Hernando Cortés with 400 men landed in Yucatan in 1519 and by 1521 they had destroyed the Aztec Empire of 200,000 people with 50,000 men at arms. Diseases, alliance with the Tlaxcalas and other anti-Aztec tribes as well as the Spanish better was strategy explain the Aztec defeat.
The first battle of Tenochtitlán took place in 1519. This city was built on a lake not very far from today Mexico City. It had many gardens, canals and pyramids and was the centre of a great civilisation. With the help of the Tlaxcalas, Cortés entered easily in the city. Montezuma was taken as hostage and his palace was looted of gold and treasure. The Aztec generals gathered their troops and the Spaniards had to flee with their gold. The Spanish lost two third of their troops. The Aztec chose a new king, Cuitlahuac, to succeed Montezuma. In the meantime the Spaniards recuperated with the Tlaxcalas and succeeded to convince the city-state of Texcoco to join them. A second battle took place against Tenochtitlán in 1521 in which Cortés mounted his guns on boats and attacked from the water. After a four-month siege the Aztec surrendered. A plague epidemic did not help the Indians. The new king, most of the nobility and more than 24,000 Aztecs were killed and Cortés became the new ruler of Mexico. Tenochtitlán was looted and destroyed.